Signaling system



March 18, 1930. w. EDISON SIGNALING SYSTEM Filed Sept. 11, 1928 III/I4 WITNESS.

Patented Mar. 18, 1930 UNITED' STATES WILLIAM LESLIE EDISON, OF WILMINGTON, DELAWARE, ASSIGNOR TO THE W. L. EDI- SON MANUFACTURING CORPORATION, OF VJILMINGTON, DELAWARE, A CORPORA- TION OF DELAWARE SIGNALING SYSTEM Application filed September 11, 1928. Serial No. 305,272.

This invention relates to a high frequency alternating current system and more particularly to means for interconnecting the tubes of an amplifying system to prevent oscillation due to mutual interaction. The system herein disclosed is particularly adapted to the amplification of radio signals.

In order to prevent oscillation in the radio frequency amplification stages of radio sets heretofore in common use various expedients have been adopted, among which may be particularly noted the use -of neutralizing condensers, potentiometers for imparting a bias upon the grid, and so called grid suppressors which consist of resistances placed in the grid circuits. In the use of these devices, the degree of amplification per stage is cut down to a considerable degree necessitating, for a satisfactory output, an excessive number of stages resulting in objectionable distortion.

It is accordingly the object of the present invention to provide an interconnecting means for the tubes of an amplifying system and a circuit including this means which produces a high degree of amplification without oscillation, distortion, or the losses referred to. The interconnecting means specificallyconsist of a novel transformer, the construction of which will be clear from the following description read in conjunction with the accompanying drawing, in which:

Fig. 1 is a diagrammatic illustration of a portion of a circuit embodying the improved amplifying system;

Fig. 2 is a vertical section through the improved transformer; and 7 Fig.3 is an elevation of the transformer showing diagrammatically the connections thereof with the other elements of an amplifying system. I I

Referring first to Figs. 2 and 3, the transformer is designated at T and consists of a base 2 on which is mounted a cylindrical cup 4 of insulating material and having a top opening in which is threaded a cap 6 of in sulating material. Suitably supported, as by a metallic bolt or rod extending through cap 6, is a metallic electrode 10, of copper for example, which is submerged in a suitable liquid 12 contained in Cup 4. The upper end of rod 8 is provided with a soldering lug 14 to which connection may be made.

' Wound on the outside of the cup or cell 4 are primary and secondary coils P and S respectively. Vfhile these coils are shown as, and preferably are, mounted on cell 4, and in spaced relationship, they may be 0therwise wound. It is, of course, obvious that the turns, shape of the cell, etc., will be determined by the circuit in which the transformer is used.

The liquid within the cell, similarly to that used in the cell described in my application for signaling system, Serial No. 288,563, filed June 27, 1928, may be of various types although water or an electrolyte solution is preferred. If it is desired to positively prevent spilling, the solution may be gelatinized as described in my prior application. 1

In Fig. 1 a number of radio frequency amplification stages are illustrated, corresponding elements of the various successive stages being designated bythe same reference characters with different subscripts appended thereto. The primary P of the first stage is shown as connected in an aerial circuit although it will be understood that current i may be produced therein from any source as, for example, from a prior amplification stage. The secondary of the first transformer T tuned by a'variable condenser C is connected to the gridland cathode respectively of a tube V containing the usual grid, plate and cathode elements, the latter of which is suitably heated. T i

The grid of tube V is connected through a resistance R with the electrode 10' of the first. transformer cell. This resistance is preferably variable and of the order of 3000 to 4000 ohms. As will be explained hereafter, the resistance R must be "of a proper value depending on the characteristics of the circuit for best operation and accordingly a variable resistance is convenient, although, for a carefully designed set, a fixed resistance of predetermined value may be used.

The plate of tube V is connected through the primary P of the. second transformer T and a suitable source of plate voltage B with v the cathode of tube V A broken connec-' tion is shown at w to indicate the inclusion of any desired number of amplification stages similar to the first, although only two-amplification stages are illustrated. As a matter of fact it is found to be possible to use five stages of radio frequency prior to the detector. 1

The transformer connections prior to the second tube V and detector V, are similar to those described in connection with the first tube and detailed explanation is believed unnecessary since the connections will beclear from Fig. 1, the parts being; correspondingly designated. A grid leak L and condenser are included in'th'e grid circuit of the detector V While not shown, it Will be clear that the plate output of the detector may be amplified at audio frequency in any desired or usual manner. Using the radio frequency amplification system shown; it is found to be particularly-advantageous to amplifythe output of i, the detector'by the means described in my prior application referred to above.

"Withconnections as described above,it is I found that, when the sizes of cells and resista'nces Rproperlypcorrespond, oscillation is 'efi'e'ctiv'ely preventedthus permitting a high degree-ofamplification. It is important that the resistances R correspond to the other elements used since variation of a resistance 1 from the, proper limits, or disconnection described above: 1 I

that there is no interposr' thereof, throws the-stage in which it .is used into violent oscillation. I It is preferable, for this reason, to employ variable resistances as It will be noted tion of anyr'resistance,potentiometer,or the like, in the grid circuit;Consequently thereis n6 diminution ofamplifi-cationwhich ordinarily results from the usual methodsof suppressing oscillation. Also, by reason. of

the direct coupling ofthe grid with the in= coming signals, thereis no dependence of amplification on wave length and it is found that uniformity of amplification at all wave lengths is obtained-J This uniformity is par- ,ticularly noticeable in receiving short waves which are suppressed by theusua'l circuits.

- Another effect is increased stability of the circuit since changeof tubes doesnot necessitate readjustmentof, the cirouitin. order to prevent oscillation; Shielding-of the radio frequency stages is also found to be 'unnecesa sary. v V M V 'Thev'action of the described 'circuit is not clearly understood and hence no explanation is given.

M 414,919, filed December 18,- 1929, contains broad clai' 'srgen'eric to its disclosure and the disclosure of this application.

What Iclaim and desire to protect by Letters Patent is:

,c'opending application, Serial it No.

1. An amplifying system including a thermionic tubehaving cathode, grid and late elements, a grid circuit joining the gri' and cathode of the tube, means for impressing signals on the gridcircuit, and a cell including a body ofvl-iquid and an electrode" contacting therewith-,- saidelectrod'e being connected with the grid.

2. An amplifying system including a there signals on the grid circuit, a cell including a body of liquid andan electrode contacting therewith, with the grid, :anda coil'i-n the. grid circuit, said cell being in the field of thecoil.

'3'. 'An amplifying system including a ther mionic tube having cathode, grid and plate elements, afgrid circuit joining the grid and cathode of the tiibe,='a transformer compris' ing primary and secondary coils,the secondary coil being in the grid circuit, and a'cell in the field of the transformer coils, saidcell including a body of liquidandan-electrode contacting therewith, said electrode being connected with the grid. 7

4;. An amplifying system including a thermionic tube having cathode, grid and plate elements, .a grid circuit-joining the grid and cathode ofthe tube, means for impressing signals on the grid circuit, and a cellincluding. a body of liquid andan electrode contacting therewith, said electrode being con-' nected with the gridthrough'a resistance.

5. An amplifying system including: a thermionictube having cathode, gridand plate elements, a grid circuit joining thegrid and cathode of the tube,'means forimpressingthermionic tube having cathode, grid and H plate elements, grid circuit-joining the grid and cathode ofv the tube, a. transformer comprising primary and secondary coils; the sec-: ondary coil being. in the grid circuit, and a cell in the field oftli e transformer coils; cell including a bo-dyof liquid and an-.:elc-

trode contacting therewith, saidelctrode being connected with the grid through a re-' sistance. I I

7 An amplifying system including a plurality-of thermionic tubes, each of which has c'athode,:grid and plate elements,-a,plate circuit joining the plate and cathodeoffone tube, a. grid circuit ;.j oin'=ing"the ;igrid and cathode of a succeeding tube, and-atrans former comprising primary and secondary coils included,- respectively ,;in the said plate and gridtcircuits, and-acell in the field of the said electrode being connected said:

transformer coils, said cell including a body of liquid and an electrode contacting therewith, said electrode being connected with the grid of said succeeding tube.

8. An amplifying system including a plurality of thermionic tubes, each of which has cathode, grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, and a transformer comprising primary and secondary coils included, respectively, in the said plate and grid circuits, and a cell in the field of the transformer coils, said cell including a body of liquid and an electrode contacting therewith, said electrode being connected with the grid of said succeeding tube through a resistance.

9. A transformer comprising a cell, and

primary and secondary coils wound about the cell, said cell including a body of liquid, and an electrode contacting with the liquid.

10. A transformer comprising a cell, and primary and secondary coils wound about the cell, said cell comprising a cup of insulating material, a body of liquid within the cup, and an electrode contacting with the liquid.

In testimony of which invention, I have hereunto set my hand at Wilmington, Del,

on this 8th day of September, 1928.

WILLIAM LESLIE EDISON. 

